v1.7.0: piani Basic/Pro/Premium/Annual + quota giornaliera

Pricing model: subscription mensili (Basic 2.99 / Pro 5.99 / Premium 9.99)
piu' Annual 49.90 one-time. Feature gating per piano (Basic = solo audio,
Pro+ = tutto). Quota giornaliera (10/30/150) con reset mezzanotte Europe/Rome.

Server: tabella daily_usage, endpoint /api/usage/consume e /status,
webhook LS gestisce subscription_* events + mappatura variant_id -> plan
via .env (LS_VARIANT_BASIC|PRO|PREMIUM|ANNUAL).

Client: gating tab in sidebar in base ai features del piano, contatore
"X/Y oggi" + bottone Upgrade, modal blocco con CTA verso landing.

server/src/server.js

@@ -5,6 +5,7 @@ import * as license from "./license.js";
 import * as updates from "./updates.js";
 import * as ls from "./lemonsqueezy.js";
 import * as dl from "./downloads.js";
+import * as usage from "./usage.js";
 
 const app = express();
 
@@ -42,6 +43,10 @@ app.post("/api/license/activate",   license.activate);
 app.post("/api/license/validate",   license.validate);
 app.post("/api/license/deactivate", license.deactivate);
 
+// Quota giornaliera
+app.get("/api/usage/status",   usage.status);
+app.post("/api/usage/consume", usage.consume);
+
 // Aggiornamenti + download firmato
 app.get("/api/latest",   updates.latest);
 app.get("/api/download", updates.download);